In the state of the art, computer printers and plotters and photocopiers generally allow the use of different forms of hard copy print media such as cut sheets of paper in standard size (8.5.times.11 inches), legal size (8.5.times.14 inches), extended size (8.5.times.17 inches), A4 size (metric), or envelopes of varying dimensions, and the like.
It is common for the manufacturers to equip for different sizes of print media by providing changeable media supply capability such as adjustable trays, multiple bins, or interchangeable media cassettes adapted for each different size of print medium. Thus, it is common for the manufacturer to provide several cassettes, trays or storage bins for different sized print media which the user must select from the control panel or manually change for each particular print job. Some machines provide limited automation in that datums, or other mechanical interface features of the cassette, provide indicators that the correct cassette has been inserted to match the user's request for a particularly sized hard copy.
Some trays and cassettes are provided with sliding guides that are manually closed about a stack of print media in one or two directions in order to align the individual sheets of the stack. These guides may be used to adjust a cassette to more than one size of print media. For example, because of the very slight dimensional difference between standard U.S. paper (8.5.times.11 inches) and the metric A4 size (8.27.times.11.69 inches), a cassette may be adapted for use with both papers by providing adjustable width guides.
Still, whenever a change in print media size is required, the user must take time to change a cassette or, using a manufacturer supplied control panel, select the appropriate tray or bin having the print media of the size matching the user's need.
Standard cassette designs either do not allow automatic machine detection of the print media dimensions or can only utilize a small sub-set of print media sizes because the print media size detection is done using fixed position switches or detection devices.
Therefore, there is a need for a more universal apparatus for holding print media of various surface area linear dimensions (length.times.width) and automatic detection of those dimensions.